Nipple-electrode assembly and method of making same

ABSTRACT

The invention relates to nipple-electrode pre-assemblies and joints, such as those used on electric furnaces, and to a method of distributing thread clearance throughout the preassembly and/or joint. This method includes: the providing of at least one lengthwise hole between each end of the nipple, said hole being substantially axial or parallel to the axis and preferably enlarged in cross-sectional area for a portion of its length at one end of the nipple; the threading of one end of the threaded nipple into the internally threaded socket of the pre-assembly electrode section to such a degree and in such a manner that by adjustment of a mechanical adjusting means to be inserted later into the lengthwise hole from the other end of the nipple, it is possible to provide or maintain a clearance between the non-load bearing flanks of the nipple threads and of said threaded electrode socket, the other end of said threaded nipple also projecting outwardly from said socket; the insertion of the mechanical adjusting means through the projecting end of the lengthwise hole and the positioning of it in the opposite end of the lengthwise hole, said means being capable of being adjusted from the end of the hole through which it is inserted so as to cause or be capable of causing relative axial movement between the nipple and the electrode section of the pre-assembly, said adjustable spacing means comprising an internally threaded outer member whose position becomes fixed in the said opposite end of said lengthwise hole of the nipple, and a corresponding externally threaded inner member capable of axial movement within said outer member; and the adjustment of the inner member by the use of a suitable tool inserted into the hole of the projecting end of the nipple so as to bring or keep the load bearing flanks of the nipple and the electrode socket section into contact securing the nipple in this position, thus providing said clearance between the non-load bearing flanks of the nipple threads and of said threaded electrode socket. The pre-assembly (or assembly) so made is thus adapted to be added to a second electrode section to complete the making of the electrode joint by threading the projecting end of the nipple into said second electrode section thereby also providing substantially even distribution of clearance between the nipple threads and the threads of the sockets of the electrode sections in the making of the final joint assembly. This thus provides and/or maintains the aforedescribed thread clearance and thereby also provides room for any excessive diametrical expansion of the nipple over that of the electrode sockets of the joint when the pre-assembly and joint are heated during service.

United States Patent 1191 Gazda Nov. 13, 1973 NIPPLE-ELECTRODE ASSEMBLY AND METHOD OF MAKING SAME Irving William Gazda, Johnson City, Tenn.

[75] Inventor:

[73] Assignee: Great Lakes Carbon Corporation, New York, N.Y.

22 Filed: Dec. 30, 1971 21 Appl. No.: 214,307

[56] References Cited UNITED STATES PATENTS 6/1970 Vail et a1. 13/18 8/1965 Kuhne 151/14 13/18 1,304,444 5/1919 Bidelman 3,084,419 4/1963 Doetsch et a1... 13/18 3,429,351 2/1969 Szalanczy 151/14 3,540,764 11/1970 Paus et a]. 13/18 3,569,609 3/1971 Fowler et al 13/18 Primary Examiner-Lowell A. Larson Attorney-Wallace F. Neyerlin 57 ABSTRACT The invention relates to nipple-electrode preassemblies and joints, such as those used on electric furnaces, and to a method of distributing thread clearance throughout the preassembly and/or joint. This method includes: the providing of at least one lengthwise hole between each end of the nipple, said hole being substantially axial or parallel to the axis and preferably enlarged in cross-sectional area for a portion of its length at one end of the nipple; the threading of one end of the threaded nipple into the internally threaded socket of the pre-assembly electrode section to such a degree and in such a manner that by adjustment of a mechanical adjusting means to be inserted later into the lengthwise hole from the other end of the nipple, it is possible to provide or maintain a clearance between the non-load bearing flanks of the nipple threads and of said threaded electrode socket, the other end of said threaded nipple also projecting outwardly from said socket; the insertion of the mechanical adjusting means through the projecting end of the lengthwise hole and the positioning of it in the opposite end of the lengthwise hole, said means being capable of being adjusted from the end of the hole through which it is inserted so as to cause or be capable of causing relative axial movement between the nipple and the electrode section of the preassembly, said adjustable spacing means comprising an internally threaded outer member whose position becomes fixed in the said opposite end of said lengthwise hole of the nipple, and a corresponding externally threaded inner member capable of axial movement within said outer member; and the adjustment of the inner member by the use of a suitable tool inserted into the hole of the projecting end of the nipple so as to bring or keep the load bearing flanks of the nipple and the electrode socket section into contact securing the nipple in this position, thus providing said clearance between the non-load bearing flanks of the nipple threads and of said threaded electrode socket.

The pre-assembly (or assembly) so made is thus adapted to be added to a second electrode section to complete the making of the electrode joint by threading the projecting end of the nipple into said second electrode section thereby also providing substantially even distribution of clearance between the nipple threads and the threads of the sockets of the electrode sections in the making of the final joint assembly. This thus provides and/or maintains the aforedescribed thread clearance and thereby also provides room for any excessive diametrical expansion of the nipple over that of the electrode sockets of the joint when the pre-assembly and joint are heated during service.

17 Claims, 13 Drawing Figures United States Patent 1 1 3,771,888 Gazda Nov. 13, 1973 NIPPLE-ELECTRODE ASSEMBLY AND METHOD OF MAKING SAME BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to the field of graphite or other carbon electrodes for electric furnaces and like equipment, wherein the electrodes are consumed in use and must be continually fed into the furnace or other equipment where they are used. It particularly relates to electrode joints that comprise a double-frusto-conical threaded connecting nipple of electrode material whose two frusto-conically tapering portions are in threaded engagement with respective frusto-conical cup-shaped socket recesses in the butt faces of the coaxially aligned electrodes and to the manner in which such a joint is assembled. However, the threaded nipples and their corresponding sockets or bore holes in the electrode sections may also have threaded sides which are parallel to the nipple axis. Such joints serve to add a new electrode to the end of a nearly consumed electrode to permit a continuous furnace operation by replenishing the electrode material in accordance with the rate of consumption.

In making such joints, one end of the nipple is screwed into place in a corresponding bore or socket of one of the electrodes to the approximate middle of the nipple and then the other electrode section is threaded to the other end of the nipple until the faces of the electrode sections are in contact. With a tapered nipple, its largest diameter is at its middle and is also at the plane of contact between the electrode sections. The threaded depth of the nipples is generally the same whether measured at the ends of the nipple or at its center and this is true whether the nipple is straight or tapered. It is also usual, with either type of connecting nipple, that in the assembled joint each thread will possess a loaded flank, wich is nearer the geometric center of the nipple, and a non-load bearing or idle flank which is opposite to the loaded flank. (That is, the idle flank is the flank nearer the ends of the nipple and the loaded flank is the flank nearer the geometric center of the nipple, and this is how these flanks are defined in the present invention). The loaded flank generally carries most, if not all, of the compressive stress between the nipple and the electrode sections.

In this type of joint, the half that is assembled first usually contains little or no clearance at the idle flank while maximum clearance occurs at the idle flank of the second half assembled.

Such electrode joints are generally mechanically weaker than the full-bodied portions of the electrodes. To maintain the strength of the joint as high as possible the nipple is normally produced from higher strength graphite than the electrode itself. In processing the nipple to higher strength the coefficient of thermal expansion (CTE) of the ultimate graphite nipple is also normally increased as compared to the graphite of the electrode stock. This higher coefficient of thermal expansion of the nipple relative to the electrode socket leads to thermal stresses within the joint during service on a furnace. Consequently the joints are particularly susceptible to breaking because of these thermal stresses which occur during heating and/or cooling of the electrodes. The high current loading of the electrode on modern electric arc furnaces frequently causes additional joint stresses by overheating of the nipple portion at the junction places between the nipple and the electrode sockets. All such thermal stresses are particularly critical with electrodes of large diameters, especially in electric arc furnaces operating at very high power levels as are used for increasing furnace productivity.

2. Description of the Prior Art There has been a well recognized need to more evenly distribute the aforedescribed clearance differences in order to reduce or counteract thermal stresses which build up due to lack of clearance to permit accommodation of the thermal expansion of the nipple and result in failure of the joint. Various methods have been proposed by those skilled in the art to accomplish substantially even distribution of thread clearance. For example, this problem and several proposed solutions for same are discussed in United States Pat.: Nos. 2,957,716; 2,970,854; 3,088,762; 3,134,616; 3,140,967; 3,517,954; 3,517,957; and 3,550,270 and also in German Pat. Nos. 1,091,253 and 1,100,838. The present invention also relates to and is concerned with a more even distribution of clearance between the threads of the nipple and the electrode sockets and consequent reduction in thermal stresses between a nipple and the electrode sections into which it is threaded and offers a novel and advantageous approach for accomplishing this.

Summary of the Invention It is an object of the present invention to provide a nipple-electrode section pre-assembly (or assembly) in which there is a more evenly distributed clearance (as compared to conventional commercial practices) between the idle or non-load bearing flanks of the nipple threads and the threads of the electrode section socket, so as-to provide room for thermal expansion of said threads and to thereby minimize the aforedescribed thermal stress conditions and to reduce the problems created by these conditions.

It is another object of this invention to substantially evenly distribute thread clearance throughout a nippleelectrode section pre-assembly, and also throughout an entire electrode joint assembly comprising two electrode sections having threaded sockets in the ends thereof and a nipple threaded into said sockets, joining the electrode sections together.

It is another object of this invention to accomplish the aforesaid more even distribution of thread clearance in an advantageous and practical manner which is also novel as compared to techniques which have been suggested or taught by the prior art for solving this problem.

The invention comprises the making of an improved nipple-electrode section pre-assembly (or assembly), such as just discussed, for use in an electrode joint comprised of said pre-assembly and a second electrode sec tion, said nipple being threaded and said sections possessing correspondingly threaded internal sockets extending inwardly from their end faces, by:

a. Providing at least one lengthwise hole between each end of the nipple, said hole being substantially axial or parallel to the axis of the nipple and preferably enlarged in cross-sectional area for a portion of its length at one end of the nipple;

b. threading one end of the threaded nipple into the internally threaded socket of the pre-assembly electrode section to such a degree and in such a manner that by adjustment of a mechanical adjusting means to be inserted later into the lengthwise hole from the other end of the nipple, it is possible to provide or maintain a clearance between the non-load bearing flanks of the nipple threads and of said threaded electrode socket, the other end of said threaded nipple also projecting outwardly from said socket;

c. inserting the mechanical adjusting means through the projecting end of the lengthwise hole and positioning it in the opposite end of the lengthwise hole, said means being capable of being adjusted from the end of the hole through which it is inserted so as to cause or be capable of causing relative axial movement between the nipple and the electrode section of the preassembly;

said adjustable spacing means comprising an internally threaded outer member whose position becomes fixed in the said opposite end of said lengthwise hole of the nipple, and a corresponding externally threaded inner member capable of axial movement within said outer member; and

d. adjusting the inner member by employing a suitable tool inserted into the hole of the projecting end of the nipple so as to bring or keep the load bearing flanks of the nipple and the electrode socket section into contact securing the nipple in this position, thus providing said clearance between the non-load bearing flanks of the nipple threads and of said threaded electrode socket.

This pre-assembly is adapted to be added to a second electrode section to complete the making of the electrode joint by threading the projecting end of the nipple into said second electrode section thereby also providing substantially even distribution of clearance between the threads of said nipple and the threads of the sockets of the electrode sections in the making of the final joint assembly.

As aforesaid, the mechanical means is adjusted by employing a suitable tool inserted into and/or down through the hole of the projecting end of the nipple. This is done by mechanically engaging the top of said means and by adjusting the externally threaded inner member within the internally threaded outer member. Typically the top of the mechanical adjusting means will possess a slot or recess of suitable size and shape for engagement by means of a suitable tool such as a screwdriver or an Allen wrench of proper length. The turning of the externally threaded inner member causes the foot end of same to contact the socket base. This threading and/or the continuation of same within the outer member forces the peripheral edges of the outer member to come into more and more forceful engagement with or against or into the walls of the lengthwise hole (or with the walls, or with the top, or with the top and walls of the lengthwise hole if it possesses the preferred enlarged portion construction) and in turn causes or is capable of causing relative axial movement of the nipple, with respect to the electrode section. The turning of the inner member of the adjusting means is continued until the load-bearing flanks of the nipple threads come or are caused to be kept in contact with the adjacent or mating flanks of the threads of the electrode socket thus securing the nipple in this position, thus also providing the desired clearance between the non-load bearing flanks of the threads of said nipple and of said threaded electrode socket. The suitable tool employed to turn the adjusting means is then, of course, removed from the lengthwise hole of the thus secured" or fixedly pre-positioned nipple in the electrode section. The pre-assembly is thus adapted to be added to a second electrode section to complete the making of the electrode joint by threading the projecting end of the nipple into said second electrode section and to thereby also provide substantially even distribution of clearance between the threads of said nipple and the threads of the sockets of the electrode sections in the making of the final joint assembly.

The invention embraces not only the method of making the pre-assembly but also the nipple-electrodesection pre-assembly itself, the method and connection improvements involved, and an electrode joint assembly made by coupling a second section to the improved nipple-electrode section pre-assembly.

In all embodiments, the invention comprises the making of an improved nipple-electrode section preassembly, such as just discussed, by employing as the adjustable spacing means a means comprising an internally threaded outer member whose position becomes fixed in the lengthwise hole of the nipple by engagement with or against or into the walls thereof (or with the walls, or with the top, or with the top and walls of the lengthwise hole' if it possesses the preferred enlarged portion construction) and a corresponding externally threaded inner member capable of axial movement within said outer member. The internally threaded outer member is typically spring actuated so as to come into contact with the walls of the lengthwise hole or with the walls of the enlarged portion of the lengthwise hole when the adjusting means reaches this part of the lengthwise hole after being inserted from the opposite end. The tips of said outer member are of such design as to be capable of exerting sufficient force to lift the nipple in the electrode section socket or to maintain it in a lifted position so as to effect the thread flank relationship described and also of such design as to become engaged with the walls of the lengthwise hole or with the surface(s) of the enlarged portion of same if this be the construction used. The adjustability of the inner member within the outer member of the adjusting means thus enables the adjustability of the spacing means within the lengthwise hole and thus can cause or be capable of causing the desired relative axial movement between the nipple and the electrode section of the pre-assembly when the inner member is adjusted within the outer member with the suitable tool.

Also, in the preferred embodiment where an end of the threaded nipple possesses a hole of enlarged crosssectional area, it is this end which is threaded into the internally threaded socket of the pre-assembly electrode section. In all embodiments the threading of the nipple is carried out to such a degree and in such a manner (hereinafter to be described) that by adjustment of the inner member of the mechanical means it is possible to provide or maintain a clearance between the non-load bearing flanks of the threads of said nipple and of said threaded electrode socket. The other end of said threaded nipple projects outwardly from said socket.

Other objects, and coincident advantages, and a complete understanding of the invention will be apparent to those skilled in the art after a study of the drawings, and a reading of the specification and claims.

Brief Description of the Drawings It has been found that the foregoing objects are achieved by making a preferred nipple-electrode section pre-assembly (or assembly) as illustrated in vertical cross-section FIG. 3, or such as illustrated in FIG. 7, and by using such a pre-assembly or assembly as part of each joint assembly used in the electrode train. FIGS. 1 and 2 illustrate a pre-assembly of the same nipple and electrode section as shown in FIG. 3 but with the members of the pre-assembly and thread flank arrangements in initial stages or positions before the final desired positioning of the members and thread clearance of FIG. 3 is obtained. FIGS. la, 2a and 3a show expanded detail of the circled portions of the threads and thread flanks of the nipple, electrode-section arrangements of FIGS. 1, 2 and 3, respectively. FIG. 4 is an expanded cross-sectional view of the indicated circled portion of FIG. 3. This Figure illustrates the preferred enlarged portion of the hole construction and also illustrates the final positioning in the enlarged portion of the lengthwise hole and in the space between the base of the nipple and the bottom of the socket of a preferred adjustable spacing meansused in carrying out the process of or in making the pre-assembly of the present invention. (It should be appreciated that the Figures are not to scale and that the enlargement of the lengthwise hole in FIGS. 1-4 and the space between the base of the nipple and the bottom of the electrode section sockets in FIGS. 3, 4 and 7 are exaggerated for illustrative purposes). FIG. 5 is a vertical side view of the preferred adjustable spacing means used in the invention, together with some useful auxiliary, but not absolutely essential components; FIG. 5a is a horizontal sectional view of the adjustable spacing means of FIG. 5, taken along the line 5a-5a of FIG. 5; and FIG. 5b is a vertical sectional view of the adjustable spacing means of FIG. 5, taken along the line 5b-5b, but with the internally threaded outer member in a closed position (as it is when being lowered through the lengthwise hole as illustrated in FIG. 1). FIG. 6 is a view similar to FIG. 1 but wherein the lengthwise hole is of uniform cross-sectional area and the adjustable spacing means is a modified version of that employed in FIGS. l-5 so as to make it more suitable for use with the uniform cross-sectional area hole. FIG. 7 is an expanded crosssectional view of the adjusting means of FIG. 6, also showing the modified spacing means in its final positioning, thus being analogous to the nipple and adjusting means positioning illustrated in FIGS. 3 and 4. FIG. 8 is a horizontal sectional view of the modified adjustable spacing means, taken along the line 8-8 of FIG. 7, and particularly illustrating its configuration which enables it to become fixed or attached to or within the walls of the lengthwise hole so that when the inner member is adjusted, the spacing means is able to cause or capable of causing (or sustaining) relative axial movement between the nipple and the electrode section of the pre-assembly.

DETAILED DESCRIPTION OF THE DRAWINGS AND OF THE PREFERRED EMBODIMENT portion of lengthwise hole 8 is shown at 8a. The top or upper surface or shoulder of this enlarged portion is shown at 8b. It is into this enlarged portion of the hole (and also the space between the base of the nipple and the bottom of the socket of the electrode section) into which the mechanical adjusting spacing means (indicated generally by the numeral 5) is finally positioned in order to carry out its function as described in the present invention. In the particular embodiment being described, the nipple was 14 inches long, had a major diameter of 10% inches, the smaller diameter of the longitudinal hole was 29/32 inch, the enlarged portion of the hole was 1% inches long and 1% inches in diameter, and the diameter of the electrode section was 20 inches. The nipple also had a one-third pitch, i.e., three threads per inch, and a taper of l to 6, i.e., its radius decreased by 1 inch for every 6 inches of length of the nipple away from the maximum diameter. The end of the nipple in which the lengthwise hole was of enlarged cross-sectional area was threaded into the socket until its major diameter, indicated generally at 3, coincided approximately with the plane of the face 4 of the electrode section and until it was hand-tight, i.e., until the threads of both the nipple and electrode socket section were fully or completely engaged, i.e., the threads were in contact on both flanks, as illustrated in FIG. la. In FIG. 2 the nipple was backed-off" a calculated slight amount such as an eighth turn (i.e., 45), thus bringing about the loosely engaged thread flank relationship illustrated in FIG. 2a. This backing off of the nipple makes it possible to pre-position the nipple in the electrode section socket in the next step of the process and, by adjustment of the mechanical means, to thus provide the desired clearance between the idle flanks of the threads of said threaded nipple and said threaded electrode socket, as illustrated and described in more detail by reference to FIGS. 3, 3a and 4.

The backing-off of 45 of the nipple in the embodiment just described is satisfactory for a nipple having a pitch and taper as set forth. In a more general sense, the number of degrees backed-off will depend on the pitch and taper of the nipple because the clearance between the threads is a function of these two variables.

For standard nipples having a one-third pitch and a taper of 1 to 6, the number of degrees backed off will typically be a value from about 45 to about for standard nipples having a one-fourth pitch (4 threads per inch) and a taper of l to 6, the number of degrees backed off will typically be a value of from about 60 to about The mechanical adjusting means 5, such as the preferred means shown in detail in FIGS. 5, 5a and 5b, and consisting of essential principal members 5a and 5b, and auxiliary, but not absolutely essential components, washers 5c and nuts 5d was then lowered down through the hole 8. The tips 5f of internally threaded outer member 5b, being spring (5e) actuated, engage the wall of hole 8 as the adjusting means 5 is lowered and it is in this position as shown in FIG. 1. In FIG. 2 the adjusting means has been further lowered in the hole to the enlarged portion thereof, wherein the tips 5f of the outer member have been spring actuated to contact the walls of the enlarged portion of the hole. However, at this stage of making the pre-assembly, the bottom or foot end of the externally threaded inner member or bolt 5a, which preferably is of enlarged cross-sectional area relative to the diameter of the bolt, typically does not yet contact the bottom of the socket of the electrode section 2.

In the next step or stage of preparing the preassembly, a suitable tool is inserted through hole 8 so as to engage member a and cause rotation thereof and cause its bottom or foot end to come in contact with the bottom of the socket of the electrode section. Further rotation of member 5a relative to member 5b pushes the foot end 5h downwardly against the base of the socket of the electrode section and the tips 5f of member Sb in the opposite direction against the nipple with sufficient force to thus cause or be capable of causing or sustaining relative axial movement between the nipple 1 and the electrode section 2 so as to provide or maintain the desired thread clearance or thread flank arrangement illustrated in FIG. 3a, and to cause or maintain a slightly increased gap or space between the base of the nipple and the electrode section socket bottom (illustrated exaggeratedly in FIGS. 3 and 4 as compared to FIG. 1 and/or FIG. 2). This prepositioning of the nipple causes the upper faces or loadbearing flank ll of the nipple (viz., the flank nearer the geometric center of the nipple) to contact the mating faces of the threads of the socket and also causes or creates a slight gap or clearance 12 at the idle or nonload bearing flank or side 13 of the thread, viz., the flank nearer the end 6 of the nipple 1.

As shown in FIGS. 4, 5, 5a and 5b, and as previously indicated, the mechanical adjusting means, (indicated generally in FIGS, 1, 2, 3 and 4 as 5), consists essentially of an internally threaded outer member 5b of such a size and design that it is adapted to press and fit tightly in the end of the nipple hole of enlarged crosssectional area by engagement with the walls, or with the top, or with the top and walls of said enlarged portion of the lengthwise hole so that its position remains fixed therein; and a correspondingly externally threaded inner member 5a, such as a threaded bolt, which is adapted for threaded engagement and axial movement with said outer member to thereby provide for the adjustability of the spacing means within said hole and also the causing or the maintaining of the aforesaid relative axial movement of the nipple with respect to the electrode section. It should be noted that this is typically accomplished in the present invention by employing what is generally referred to as a toggle bolt for members 5a and 5b. As shown in FIGS. 5 and 5a, member 5b includes two trough shaped leafs which are sheet metal stamped into a hingelike relationship with a sturdy pivot member 5g which is internally threaded. Studs at 180' on the pivot member cooperating with holes in the inner ends of the leafs permit the attainment of this hinge-like relationship. Wire spring 5e, which is coiled around one of the studs of the pivot member and whose ends push against the inner surfaces of the trough shaped leafs 5f, causes outer member 5b to contact and engage the walls of the'enlarged portion 8a of the hole 8 as the adjusting means is lowered and positioned therein. When inner member 5a is then caused to be threaded through member 5b, the tips of member 5b are caused to slide slightly up the walls of the enlarged portion of the hole and come into contact also with the top or shoulders 8b thereof. The more the inner member 5a is tightened, the greater is the engagement of the tips of the outer member with the walls, or with the top, or with the top and walls of said enlarged portion of the lengthwise hole.

Washers 5c and nuts 5d, although not absolutely essential are very helpful in carrying out the invention because they serve to guide the threaded bolt or inner member 5a down the lengthwise hole and to'maintain the bolt in a substantially axial position in the hole. Three nuts 5d and two washers 5c are typically used, one of the washers being tightly engaged between the head of the bolt and one of the nuts, and the other washer being tightly engaged between the other two nuts, toward mid length of the bolt. It should be appreciated that adjusting means and complementing members having features other than those described herein may also be employed in the present invention so long as they have the equivalent of the two essential members 5a and 5b and perform the same functions as described.

It should be noted that the relative axial movement or positioning of the nipple with respect to the electrode section may be and preferably is caused in other ways than by use of adjusting means 5 alone, such as by use ofa ring 1 as described in U. S. Pat. No. 3,550,270, or a centering jig as described in U. S. Pat. No. 3,517,954. If such preferred alternatives are used, then the mechanical adjusting means is employed more to maintain and/or keep or sustain the desired thread clearance rather than to also establish or provide same. If the adjusting means is used in this manner it is considered the same as or the equivalent of being capable of causing the desired relative axial movement between the nipple and the electrode section of the preassembly.

Inner member Sa possesses a keying means such as a slot or a cornered recess therein, so that it may be turned by means of a suitable tool, such as a screwdriver or Allen wrench, inserted down or through hole 8 and turned therein. Regardless of whether it is employed alone, or with an alternative such as the aforediscussed ring or centering jig, in the final positioning of the nipple in the pre-assembly, inner member 5a is always adjusted within hole 8 until the nipple is fixed or secured firmly in place in the electrode section socket, with the load bearing thread flanks in contact, and with clearance between the non-load bearing flanks as shown in FIG. 3a.

The alternative embodiment of the invention illustrated by FIGS. 6-8 shows that it is not necessary to enlarge a portion of the lengthwise hole in order to attain and/or maintain the desired relative axial movement between the nipple and the electrode section of the pre-assembly. Instead the internally threaded outer member of the adjusting means may be so designed or modified or constructed and of such dimension that its tips or outer periphery will dig or cut into the wall of the lengthwise hole of the graphite nipple and thus grip the nipple with sufficient firmness as to accomplish the same end result of relative axial movement as is achieved in the embodiment of the enlarged hole construction previously described. In FIGS. 68 this was accomplished by suitably machining the trough shaped leafs of the same type of toggle bolt as employed in the preferred embodiment so that the ends of the leafs were made quite pointed" as illustrated by 5] in FIGS. 7 and 8.

Rather than dig or cut into the wall of the lengthwise hole, as shown in FIG. 7, the adjusting means may also be so designed and its outer member so positioned near the foot end of inner member 5a that the tips or outer periphery of the outer member will dig into the base 6 of the nipple (if sufficient clearance space is provided between the nipple base and the bottom of the socket of the electrode section). In this alternative, because of the location of the inner member within the lengthwise hole, the adjusting means is still considered positioned in the end of the lengthwise hole, as stated in the claims.

The nuts and bolts of FIG. are not shown in FIG. 7 but it should, of course, be appreciated that they may also be employed in this embodiment of the invention.

As previously mentioned, inner member or bolt 5a is preferably provided with a flange 5h of enlarged crosssectional area at its base or foot end so as to provide increased area of contact between the end of the bolt and the socket base and thus, also, more balanced lifting or sustaining of the nipple in its raised position illustrated in FIGS. 3, 3a, 4 and 7.

It should also be appreciated that more than one hole 8 and mechanical adjusting means 5 may be employed in carrying out the invention, although this is not generally necessary or desirable. Any such hole or holes used should be substantially axial and/or parallel to the nipple axis so as to assure even balancing of the nipple in the socket of the pre-assembly electrode section and thus guard against cocking of the nipple therein.

When an electrode section-nipple preassembly as described herein is added to a second electrode section of an electric furnace column or train, the nipple in the resulting S-membered joint (viz., two electrode sections with the nipple half-threaded into each) will be so located that there will be a substantially even distribution of clearance between the idle flanks of the threads of both halves of the nipple in the electrode section sockets of the final joint assembly, rather than the common and objectionable condition typically encountered in the prior art of no clearance at the idle flank of the threads of the nipple-half assembled first and maximum clearance at the idle flank of the threads of the second nipple-half assembled. Consequently there is a reduction in the thermal stresses between the nipple and the electrode sections into which it is threaded with the result that there is a reduction in the degree of splitting and breakage of the joint in furnace operation.

The net effect, therefore, of centering or balancing the nipple in the joint, is that there are fewer mechanical breakdowns or failure in the operation of the furnace. There are also other advantages inherent in making the nipple-electrode section assemblies and joints in accordance with the present invention. For example, the incidence of thread stripping from the sockets of the threaded electrode sections is virtually precluded because of the more uniform thread loading attending the centering of the nipple.

It is to be understood that the invention is not limited to the specific details which have been offered merely for illustrative purposes and that modifications may be made within the scope of the appended claims without departing from the spirit of the invention.

I claim:

1. A method of producing an electrode sectionnipple assembly for use in an electrode joint comprised of said assembly and a second electrode section, said nipple being threaded and said sections possessing correspondingly threaded internal sockets extending inwardly from their end faces, which comprises:

a. Providing at least one lengthwise hole between each end of the nipple, said hole being substantially axial or parallel to the axis of the nipple;

b. threading one end of the threaded nipple into the internally threaded socket of the assembly electrode section to such a degree and in such a manner that by adjustment of a mechanical adjusting means to be inserted later into the length-wise hole from the other end of the nipple, it is possible to provide or maintain a clearance between the nonload bearing flanks of the nipple threads and of said threaded electrode socket, the other end of said threaded nipple also projecting outwardly from said socket;

c. inserting the mechanical adjusting means through the projecting end of the lengthwise hole and positioning it in the opposite end of the lengthwise hole, said means being capable of being adjusted from the end of the hole through which it is inserted so as to cause or be capable of causing relative axial movement between the nipple and the electrode section of the assembly;

said adjustable spacing means comprising an internally threaded outer member whose position becomes fixed in the said opposite end of said lengthwise hole of the nipple, and a corresponding externally threaded inner member capable of axial movement within said outer member; and

d. adjusting the inner member by employing a suit able tool inserted into the hole of the projecting end of the nipple so as to bring or keep the load bearing flanks of the nipple and the electrode socket section into contact securing the nipple in this position, thus providing said clearance between the non-load bearing flanks of the nipple threads and of said threaded electrode socket;

said assembly being adapted to be added to a second electrode section to complete the making of the electrode joint by threading the projecting end of the nipple into said second electrode section thereby also providing substantially even distribu tion of clearance between the nipple threads and the threads of the sockets of the electrode sections in the making of the final joint assembly.

2. A method of producing an electrode sectionnipple assembly for use in an electrode joint comprised of said assembly and a second electrode section, said nipple being threaded and said sections possessing correspondingly threaded internal sockets extending inwardly from their end faces, which comprises:

a. Providing at least one lengthwise hole between each end of the nipple, said hole being substantially axial or parallel to the axis of the nipple and enlarged in cross-sectional area for a portion of its length at one end of the nipple;

b. threading the end of the threaded nipple in which the lengthwise hole is of enlarged cross-sectional area into the internally threaded socket of the assembly electrode section to such a degree and in such a manner that by adjustment of a mechanical adjusting means to be inserted later into the lengthwise hole from the other end of the nipple, it is possible to provide or maintain a clearance between the non-load bearing flanks of the nipple threads and of said threaded electrode socket, the other end of said threaded nipple also projecting outwardly from said socket;

c. inserting the mechanical adjusting means through the projecting end of the lengthwise hole of smaller cross-sectional area and positioning it in the opposite enlarged end of the lengthwise hole, said means being capable of being adjusted from the end of the hole through which it is inserted so as to cause or be capable of causing relative axial movement between the nipple and the electrode section of the assembly;

said adjustable spacing means comprising an internally threaded outer member whose position becomes fixed in the said opposite enlarged end of said lengthwise hole of the nipple, and a corresponding externally threaded inner member capable of axial movement within said outermember; and

d. adjusting the inner member by employing a suitable tool inserted into the hole of the projecting end of the nipple so as to bring or keep the load bearing blanks of the nipple and the electrode socket section into contact securing the nipple in this position, thus providing said clearance between the non-load bearing flanks of the nipple threads and of said threaded electrode socket;

said assembly being adapted to be added to a second electrode section to complete the making of the electrode joint by threading the projecting end of the nipple into said second electrode section thereby also providing substantially even distribution of clearance between the nipple threads and the threads of the sockets of the electrode sections in the making of the final joint assembly.

3. A method according to claim 2 wherein said internally threaded outer member becomes fixed in said opposite enlarged end of said lengthwise hole of the nipple by engagement with the walls, or with the top, or with the top and walls of said enlarged portion of the lengthwise hole.

4. A method according to claim 1 wherein in step b the nipple is hand-tightened as far as it will go into the electrode socket and is then backed off that amount required to provide the desired clearance between the threads by adjustment of the mechanical means.

5. A method according to claim 1 wherein the adjustable spacing means is a toggle bolt, the internally threaded outer member of which is spring actuated so as to come into contact with the walls of the lengthwise hole and wherein the tips of said outer member are of such design as to be capable of exerting sufficient force to maintain the nipple in a lifted position in the electrode section socket so as to effect the thread flank relationship described and also of such design as to become engaged with the walls of said lengthwise hole so that the inner member of the adjusting means can cause or be capable of causing the desired relative axial movement between the nipple and the electrode section of the assembly when it is adjusted within the outer member with the suitable tool.

6. A method according to claim 2 wherein the adjustable spacing means is a toggle bolt, the internally threaded outer member of which is spring actuated so as to come into contact with the walls of the enlarged portion of the lengthwise hole and wherein the tips of said outer member are of such design as to be capable of exerting sufficient force to maintain the nipple in a lifted position in the electrode section socket so as to effect the thread flank relationship described and also of such design as to become engaged with the walls or the top or the top and walls of said enlarged portion of the lengthwise hole so that the inner member of the adjusting means can cause or be capable of causing the desired relative axial movement between the nipple and the electrode section of the assembly when it is adjusted with the outer member with the suitable tool.

7. A method according to claim 1 wherein the externally threaded inner member of said adjustable spacing means is an elongated threaded bolt whose head is rotatable by means of a screwdriver.

8. A method according to claim 7 wherein three nuts and two washers are located on the bolt, one of the washers tightly engaged between the head of the bolt and one of the nuts, and the other washer tightly engaged between the other two nuts, said washers and nuts serving to guide the threaded bolt down the lengthwise hole and also helping to maintain the bolt in a substantially axial position in the hole.

9. A method according to claim 7 wherein the foot end of the bolt is of enlarged cross-sectional area, relative to the diameter of the bolt, so as to provide increased area of contact between the end of the bolt and the socket base.

10. A method according to claim 8 wherein the foot end of the bolt is of enlarged cross-sectional area, relative to the diameter of the bolt, so as to provide increased area of contact between the end of the bolt and the socket base.

11. An electrode section nipple assembly comprising:

a. An electrode section containing internally threaded sockets extending into the section from each of its end faces;

b. a threaded nipple, having at least one lengthwise hole therein which is substantially axial or parallel to the axis of the nipple, threaded into and positioned in one of the sockets of said electrode section with the load bearing flanks of the nipple threads, which are the flanks nearer to the geometric center than to the ends of the nipple, in contact with the mating faces of the threads of the electrode section socket and with a space between the base of the nipple and the bottom of the electrode section socket; and

c. a mechanically adjustable spacing means situated within the lengthwise hole of the nipple between the base of the nipple and the bottom of the socket of the electrode section and which is adjustable from the opposite end of the hole in the nipple;

said adjustable spacing means comprising an internally threaded outer member which is installed in the concealed end of said lengthwise hole of the nipple from the opposite open end of the lengthwise hole after the nipple has been threaded into the assembly electrode section socket and whose position becomes fixed in said concealed end, and a correspondingly externally threaded inner member having engagement means thereon and being capable of axial movement within said outer member, whereby said spacing means is adjusted into contact with said socket bottom to hold said load bearing thread flanks in contact.

12. An electrode section nipple assembly comprising:

a. An electrode section containing internally threaded sockets extending into the section from each of its end faces;

b. a threaded nipple, having at least one lengthwise hole therein which is substantially axial or parallel to the axis of the nipple and enlarged in crosssectional area for a portion of its length at one end of the nipple, threaded into and positioned in one of the sockets of said electrode section with the load bearing flanks of the nipple threads, which are the flanks nearer to the geometric center than to the ends of the nipple, in contact with the mating faces of the threads of the electrode section socket and with a space between the base of the nipple and the bottom of the electrode section socket; and

c. a mechanically adjustable spacingmeans situated within the lengthwise hole of the nipple and the space between the base of the nipple and the bottom of the socket of the electrode section and which is adjustable from the opposite end of the hole in the nipple;

said adjustable spacing means comprising an internally threaded outer member which is installed in the concealed enlarged end of said lengthwise hole of the nipple from the opposite open end of the lengthwise hole after the nipple has been threaded into the assembly electrode section socket and whose position becomes fixed in said concealed, enlarged end, and a correspondingly externally threaded inner member having engagement means thereon and being capable of axial movement within said outer member, whereby said spacing means is adjusted into contact with said socket bottom to hold said load bearing thread flanks in contact.

13. An electrode section nipple assembly according to claim 11 wherein the adjustable spacing means is a toggle bolt, the internally threaded outer member of which is spring actuated into contact with the walls of the lengthwise hole and wherein the tips of said outer member exert sufficient force to maintain the nipple in a lifted position in the electrode section socket so as to effect the thread flank relationship described after becoming engaged with the walls of said lengthwise hole when the inner member is adjusted within the outer member with a suitable tool.

14. An electrode section nipple assembly according to claim 11 wherein the externally threaded inner member of said adjustable spacing means is an elongated threaded bolt whose head is rotatable by means of a screwdriver.

15. An electrode section nipple assembly according to claim 11 wherein there are located on the bolt three nuts and two washers, one of the washers tightly engaged between the head of the bolt and one of the nuts, and the other washer tightly engaged between the other two nuts, said washers and nuts having served to guide the threaded bolt down the lengthwise hole and said washers and nuts also having served to help maintain the bolt in a substantially axial position in the hole.

16. An electrode section nipple assembly according to claim 14 wherein the foot end of the bolt is of enlarged cross-sectional area, relative to the diameter of the bolt, so that it provides increased area of contact between the end of the bolt.

17. An electrode section nipple assembly according to claim 15 wherein the foot end of the bolt is of enlarged cross-sectional area, relative to the diameter of the bolt, so that it provides increased area of contact between the end of the bolt and the socket base. 

1. A method of producing an electrode section-nipple assembly for use in an electrode joint comprised of said assembly and a second electrode section, said nipple being threaded and said sections possessing correspondingly threaded internal sockets extending inwardly from their end faces, which comprises: a. Providing at least one lengthwise hole between each end of the nipple, said hole being substantially axial or parallel to the axis of the nipple; b. threading one end of the threaded nipple into the internally threaded socket of the assembly electrode section to such a degree and in such a manner that by adjustment of a mechanical adjusting means to be inserted later into the length-wise hole from the other end of the nipple, it is possible to provide or maintain a clearance between the non-load bearing flanks of the nipple threads and of said threaded electrode socket, the other end of said threaded nipple also projecting outwardly from said socket; c. inserting the mechanical adjusting means through the projecting end of the leNgthwise hole and positioning it in the opposite end of the lengthwise hole, said means being capable of being adjusted from the end of the hole through which it is inserted so as to cause or be capable of causing relative axial movement between the nipple and the electrode section of the assembly; said adjustable spacing means comprising an internally threaded outer member whose position becomes fixed in the said opposite end of said lengthwise hole of the nipple, and a corresponding externally threaded inner member capable of axial movement within said outer member; and d. adjusting the inner member by employing a suitable tool inserted into the hole of the projecting end of the nipple so as to bring or keep the load bearing flanks of the nipple and the electrode socket section into contact securing the nipple in this position, thus providing said clearance between the non-load bearing flanks of the nipple threads and of said threaded electrode socket; said assembly being adapted to be added to a second electrode section to complete the making of the electrode joint by threading the projecting end of the nipple into said second electrode section thereby also providing substantially even distribution of clearance between the nipple threads and the threads of the sockets of the electrode sections in the making of the final joint assembly.
 2. A method of producing an electrode section-nipple assembly for use in an electrode joint comprised of said assembly and a second electrode section, said nipple being threaded and said sections possessing correspondingly threaded internal sockets extending inwardly from their end faces, which comprises: a. Providing at least one lengthwise hole between each end of the nipple, said hole being substantially axial or parallel to the axis of the nipple and enlarged in cross-sectional area for a portion of its length at one end of the nipple; b. threading the end of the threaded nipple in which the lengthwise hole is of enlarged cross-sectional area into the internally threaded socket of the assembly electrode section to such a degree and in such a manner that by adjustment of a mechanical adjusting means to be inserted later into the lengthwise hole from the other end of the nipple, it is possible to provide or maintain a clearance between the non-load bearing flanks of the nipple threads and of said threaded electrode socket, the other end of said threaded nipple also projecting outwardly from said socket; c. inserting the mechanical adjusting means through the projecting end of the lengthwise hole of smaller cross-sectional area and positioning it in the opposite enlarged end of the lengthwise hole, said means being capable of being adjusted from the end of the hole through which it is inserted so as to cause or be capable of causing relative axial movement between the nipple and the electrode section of the assembly; said adjustable spacing means comprising an internally threaded outer member whose position becomes fixed in the said opposite enlarged end of said lengthwise hole of the nipple, and a corresponding externally threaded inner member capable of axial movement within said outer member; and d. adjusting the inner member by employing a suitable tool inserted into the hole of the projecting end of the nipple so as to bring or keep the load bearing blanks of the nipple and the electrode socket section into contact securing the nipple in this position, thus providing said clearance between the non-load bearing flanks of the nipple threads and of said threaded electrode socket; said assembly being adapted to be added to a second electrode section to complete the making of the electrode joint by threading the projecting end of the nipple into said second electrode section thereby also providing substantially even distribution of clearance between the nipple threads and the threads of the sockets of the electrode sections in the making of the final joint assembly.
 3. A method acCording to claim 2 wherein said internally threaded outer member becomes fixed in said opposite enlarged end of said lengthwise hole of the nipple by engagement with the walls, or with the top, or with the top and walls of said enlarged portion of the lengthwise hole.
 4. A method according to claim 1 wherein in step b the nipple is hand-tightened as far as it will go into the electrode socket and is then backed off that amount required to provide the desired clearance between the threads by adjustment of the mechanical means.
 5. A method according to claim 1 wherein the adjustable spacing means is a toggle bolt, the internally threaded outer member of which is spring actuated so as to come into contact with the walls of the lengthwise hole and wherein the tips of said outer member are of such design as to be capable of exerting sufficient force to maintain the nipple in a lifted position in the electrode section socket so as to effect the thread flank relationship described and also of such design as to become engaged with the walls of said lengthwise hole so that the inner member of the adjusting means can cause or be capable of causing the desired relative axial movement between the nipple and the electrode section of the assembly when it is adjusted within the outer member with the suitable tool.
 6. A method according to claim 2 wherein the adjustable spacing means is a toggle bolt, the internally threaded outer member of which is spring actuated so as to come into contact with the walls of the enlarged portion of the lengthwise hole and wherein the tips of said outer member are of such design as to be capable of exerting sufficient force to maintain the nipple in a lifted position in the electrode section socket so as to effect the thread flank relationship described and also of such design as to become engaged with the walls or the top or the top and walls of said enlarged portion of the lengthwise hole so that the inner member of the adjusting means can cause or be capable of causing the desired relative axial movement between the nipple and the electrode section of the assembly when it is adjusted with the outer member with the suitable tool.
 7. A method according to claim 1 wherein the externally threaded inner member of said adjustable spacing means is an elongated threaded bolt whose head is rotatable by means of a screwdriver.
 8. A method according to claim 7 wherein three nuts and two washers are located on the bolt, one of the washers tightly engaged between the head of the bolt and one of the nuts, and the other washer tightly engaged between the other two nuts, said washers and nuts serving to guide the threaded bolt down the lengthwise hole and also helping to maintain the bolt in a substantially axial position in the hole.
 9. A method according to claim 7 wherein the foot end of the bolt is of enlarged cross-sectional area, relative to the diameter of the bolt, so as to provide increased area of contact between the end of the bolt and the socket base.
 10. A method according to claim 8 wherein the foot end of the bolt is of enlarged cross-sectional area, relative to the diameter of the bolt, so as to provide increased area of contact between the end of the bolt and the socket base.
 11. An electrode section nipple assembly comprising: a. An electrode section containing internally threaded sockets extending into the section from each of its end faces; b. a threaded nipple, having at least one lengthwise hole therein which is substantially axial or parallel to the axis of the nipple, threaded into and positioned in one of the sockets of said electrode section with the load bearing flanks of the nipple threads, which are the flanks nearer to the geometric center than to the ends of the nipple, in contact with the mating faces of the threads of the electrode section socket and with a space between the base of the nipple and the bottom of the electrode section socket; and c. a mechanically adjustable spacing means situated wIthin the lengthwise hole of the nipple between the base of the nipple and the bottom of the socket of the electrode section and which is adjustable from the opposite end of the hole in the nipple; said adjustable spacing means comprising an internally threaded outer member which is installed in the concealed end of said lengthwise hole of the nipple from the opposite open end of the lengthwise hole after the nipple has been threaded into the assembly electrode section socket and whose position becomes fixed in said concealed end, and a correspondingly externally threaded inner member having engagement means thereon and being capable of axial movement within said outer member, whereby said spacing means is adjusted into contact with said socket bottom to hold said load bearing thread flanks in contact.
 12. An electrode section nipple assembly comprising: a. An electrode section containing internally threaded sockets extending into the section from each of its end faces; b. a threaded nipple, having at least one lengthwise hole therein which is substantially axial or parallel to the axis of the nipple and enlarged in cross-sectional area for a portion of its length at one end of the nipple, threaded into and positioned in one of the sockets of said electrode section with the load bearing flanks of the nipple threads, which are the flanks nearer to the geometric center than to the ends of the nipple, in contact with the mating faces of the threads of the electrode section socket and with a space between the base of the nipple and the bottom of the electrode section socket; and c. a mechanically adjustable spacing means situated within the lengthwise hole of the nipple and the space between the base of the nipple and the bottom of the socket of the electrode section and which is adjustable from the opposite end of the hole in the nipple; said adjustable spacing means comprising an internally threaded outer member which is installed in the concealed enlarged end of said lengthwise hole of the nipple from the opposite open end of the lengthwise hole after the nipple has been threaded into the assembly electrode section socket and whose position becomes fixed in said concealed, enlarged end, and a correspondingly externally threaded inner member having engagement means thereon and being capable of axial movement within said outer member, whereby said spacing means is adjusted into contact with said socket bottom to hold said load bearing thread flanks in contact.
 13. An electrode section nipple assembly according to claim 11 wherein the adjustable spacing means is a toggle bolt, the internally threaded outer member of which is spring actuated into contact with the walls of the lengthwise hole and wherein the tips of said outer member exert sufficient force to maintain the nipple in a lifted position in the electrode section socket so as to effect the thread flank relationship described after becoming engaged with the walls of said lengthwise hole when the inner member is adjusted within the outer member with a suitable tool.
 14. An electrode section nipple assembly according to claim 11 wherein the externally threaded inner member of said adjustable spacing means is an elongated threaded bolt whose head is rotatable by means of a screwdriver.
 15. An electrode section nipple assembly according to claim 11 wherein there are located on the bolt three nuts and two washers, one of the washers tightly engaged between the head of the bolt and one of the nuts, and the other washer tightly engaged between the other two nuts, said washers and nuts having served to guide the threaded bolt down the lengthwise hole and said washers and nuts also having served to help maintain the bolt in a substantially axial position in the hole.
 16. An electrode section nipple assembly according to claim 14 wherein the foot end of the bolt is of enlarged cross-sectional area, relative to the diameter of the bolt, so that it provides increased area of contact bEtween the end of the bolt.
 17. An electrode section nipple assembly according to claim 15 wherein the foot end of the bolt is of enlarged cross-sectional area, relative to the diameter of the bolt, so that it provides increased area of contact between the end of the bolt and the socket base. 